How much ownership should a founder of a startup expect to give to VCs in a Series A financing?

These days it will be more likely that your first round would come from an Angel or group of Angels rather than from a managed fund. Angels are much more active right now investing in pure start ups. For this reason it is critically important to pick the right fit for your project. An investor should always bring more to the table than money. Expertise and access come to mind.

In any investor situation some sort of metric will be employed to help determine the valuation of the project. Anything pre-revenue better have an incredible team in place no matter how wonderful the concept seems. Once a valuation is agreed upon, the percentage of shares distributed comes down to math. It's a bit of art and science, so it's helpful to have someone who has successfully raised equity on the team or close by.